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Old 25th March 2014, 09:28 PM   #601
jps1964 is offline jps1964  Germany
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... and for the last publishing...
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Old 25th March 2014, 10:15 PM   #602
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Nice. It's tall enough to not fit in many places though. I wonder if it could be shortened? I like the idea of replacing 3-terminal regulators with it.

However for that I'd make it zener regulated so people don't try to use them in a circuit that needs a constant voltage.

I would add decoupling to the input and output, because we don't know what it would be plugged into.
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Old 25th March 2014, 10:58 PM   #603
jps1964 is offline jps1964  Germany
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like regulators, decoupling caps are to place externally and the user choose the capacitor value and type (to ground).
The PCB fits on a Fischer Elektronik SK104.
Direct Heated Tubes needs a constant voltage (300B +5VDC) done by, rectifiers, caps, pre-regulator +5VDC+1.8VDC, caps, and K-Multiplier to achieve the needed +5VDC for the first pole of the heather; connect the current sink (2SC5171 + BC817-40 + 1k0 to +6.8VDC + 0.6V/1.2A = 0.5R@2W/1%/2512 resistor) on the second pole ... in french, le tour est joué!
There is here a Rob Coleman DHT thread...
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Old 25th March 2014, 11:00 PM   #604
jps1964 is offline jps1964  Germany
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if it is too big, double sided SMD placement!
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Old 26th March 2014, 12:13 AM   #605
jps1964 is offline jps1964  Germany
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... CFP-gyrator + current sink...
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Old 26th March 2014, 12:51 AM   #606
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For bias current, it's diminishing returns after 100mA, and I'd set it low at 25mA so it's not wasting 1/4 of its power out of the box. At 25mA the emitter resistor for the current sink will dissipate only 17mW, so don't need large resistors here. Add some vias for users to solder in their own sink preference?

If the current sink feed resistor is 56k it will work up to 100V (resistor will be hot though, how hot should we let resistors get for longevity?).
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Old 29th March 2014, 10:45 AM   #607
WT is offline WT
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I builde K Multiplier but I can not find 2sa1930 and 2sc5171. So I use Bd140, bd139 instead. It works with no load and 1.2k (around 20ma load) as load. However when connect to c4200uF and salas shunt reg which draw 140 ma, led at k multiplier turn on and voltage drop is high(6v). Where should I look for to solve this.
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Old 29th March 2014, 08:43 PM   #608
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Assuming you haven't made any wiring errors, do you have lytics right at the input and output?

The BD139 is a different transistor depending on who you get it from, some versions are slow. If you use the wrong transistor for this position it can cause oscillation. Which transistors do you have that you could use here?
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Old 29th March 2014, 10:01 PM   #609
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Quote:
Originally Posted by WT View Post
I builde K Multiplier but I can not find 2sa1930 and 2sc5171. So I use Bd140, bd139 instead. It works with no load and 1.2k (around 20ma load) as load. However when connect to c4200uF and salas shunt reg which draw 140 ma, led at k multiplier turn on and voltage drop is high(6v). Where should I look for to solve this.
Mouser has both in stock. Shipping to you should be small. Regards
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Old 1st April 2014, 05:44 AM   #610
WT is offline WT
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Quote:
Originally Posted by keantoken View Post
Assuming you haven't made any wiring errors, do you have lytics right at the input and output?

The BD139 is a different transistor depending on who you get it from, some versions are slow. If you use the wrong transistor for this position it can cause oscillation. Which transistors do you have that you could use here?
I have 4200uF electrolytic at the input and output. Is it too much on the output?

For Transistor, I can have

PNP MJE2955T, TIP32C, TIP127, TIP42C.
NPN MJE3055, TIP31C, TIP122, TIP41C.
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